A sliding window for a building includes a stationary frame, an opening leaf, a motorized drive device, a fittings system, and a locking control device. The motorized drive device includes an electromechanical actuator, a flexible element, and a drive arm. The flexible element drives movement of the opening leaf with respect to the stationary frame when the actuator is electrically activated. The arm is connected both to a frame of the opening leaf and to the flexible element. The locking control device collaborates with a lock of the fittings system and is actuated by the flexible element when the actuator is electrically activated. The drive arm supports the locking control device. The fittings system also includes an errorproofing system. The locking control device actuates the lock following activation of the errorproofing system and when the actuator is electrically activated.